1. Field of the Invention
The present invention relates to a dispenser for dispensing a substance, in particular, a pneumatic dispenser including a housing, a dispensing device located in the housing and having an elongate press-out member for ejecting the substance and supported in the housing for displacement in a longitudinal direction, and a metering device for presetting a metered amount of the substance to be dispensed by the dispensing device and having an adjustment member for adjusting the metered amount, an entrain member cooperating with the press-out member, and a return device for displacing the entrain member from its end position to its initial position.
2. Description of the Prior Art
Dispensers of the type described above are used for delivering a metered amount of a substance, e.g., from a cartridge or a bag. The substance can consist of one or more components stored in one or several cartridges. The dispenser includes a housing, a dispensing device, and a metering device. In the housing, there is provided space for receiving one or more cartridges from which a substance is dispensed, in particular, is press-out or ejected. At certain applications, e.g., with chemical dowels, the dispensed amount of the substance is defined by the requirements of a used chemical dowel. The metering device permits the user to dispense, in a time-saving manner, a precise amount, e.g., for filling a bore. For adjusting the metered amount of a substance, the metering device includes an adjustment member.
U.S. Pat. No. 5,020,693 discloses a pneumatic dispenser including a housing, a dispensing device for storing and delivering a substance and having an elongate press-out member, a metering device for preliminary selecting a metered amount of the substance to be dispensed by the dispensing device and an actuation mechanism for actuating the dispensing device. The metering device has a return device, an adjustment member for adjusting the metered amount, and an entrain member which cooperates with the press-out member and is displaced from its end position to its initial position by the return device. The press-out member is supported in the housing for a longitudinal displacement therein. The press-out member has a plurality of piston rods for ejecting, e.g., a cartridge filled with a substance. The metering device is provided with at least one stop provided on the housing and displaceable in the longitudinal direction of the press-out member securable with a locking screw.
The drawback of the metering device of U.S. Pat. No. 5,020,693 consists in that the screwed-down stop is displaced at least somewhat by the return device, whereby the predetermined metered amount of the substance can be changed.
A further drawback of the metering device of U.S. Pat. No. 5,020,693 consists in that the adjustment member does not insure a convenient and sufficiently precise adjustment of the metered amount.
Accordingly, an object of the present invention is to provide a dispenser that can be economically manufactured and, at the same time, would insure a precise and convenience adjustment of the metered amount.
Another object of the present invention is to provide a dispenser in which an undesirable change of the metered amount is prevented.